Loudspeaker



July 19, 1938. J p, QUAM 2,124,338

LOUDSPEAKER Filed April s, 1935 2 sheets-sheet 1 July 19, 193s. J. P.QUAM 2,124,338

I LOUDSPEAKER Filed April, 1935 2 Sheets-Sheet 2 catto" speaker.

Patented July 19, 1938 uNrrl-:D s

' SEP 9- oF-Fic f l1.oUlisrlinKFR James P. Quam, Chicagm'lll., assignerto Quam- Chicago, Ill., a corporation Nichols Company, of MissouriApplication Aprii s, 1935, seal No.` 14,389

' 16v Claims.

My invention relates in general vto loudspeakers, and particularlyloudspeakers with the cone type diaphragm and a vibratory unit therefor,ordinarily known as a magnetic type speaker.

Diiculty is encountered kin, the presentmagneticvr type loudspeakers inthatitis not possible to obtain the volumeor `the faithfulness ofreproduction over the entire band of frequencies `obtained from thedynamic,` type loudspeaker.

Chatteringand distortionroften developwhen the speakeris operated athigh volumes so as to impair reproduction.

A further disadvantage to the present magnetic type speaker, incomparison. with a dynamic speaker, is they fact that it is less sturdy,,and has ashorter life. Furthermore, Yit does' not lend `itself toshipment and handling as satisfactorily Aas thedynamic type.- g 5.

It is an object of my inventiony ;to `provide an improved magnetic. typeof loudspeaker.

A `further object `is to provide an improved vibratory Aunit for a conetypey diaphragm..loud

It is also an object to provide .a magneticv type loudspeaker which,will,y faithfully reproduce. at large volume aradioy broadcastoversubstantially the entire band of frequencies.

One of the features of my-improved driving -unit isthe provision vofalaminat'ed. permanent magnet comprising closed .ring-shaped bodymembers, in which said laminations are punched out on apunch press. v .fAn additional feature isftlie,` provision of a -pair of laminated polepieces. adapted; to carry a `laminated yarmature anda field coiltherebeytween, with thethree -elements designed to be mounted betweenthe laminations of the vperma nent magnetas afframe.furtheI elements.

-A further feature of my invention is ythe provision of a vibratoryunitior a loudspeakerwhich may be completelyassembled and then quicklymounted directly onthe usualframe support yfor the cone-shaped-diaphragmofthe'speaker. y vIt is also al featureotmyinvention to proalong the une5 'cf Fig. 3.

will be apparent from theiollowing descriptinn iftaken with thedrawings, in which: r

Fig. 1 is a front elevation of the completely assembled loudspeaker.

Fig. 2; is a rear elevation thereof.

Fig. 3 is a fragmentary .rear elevation partly in 'M- section of thevibratory or driving forthe speaker.` f.

Fig.I 4 is a similar view to that of Fig. 3,shovv ing the pole piecesoutside the armature.

Fig. 5 is a sectional view of the driving unit ing in addition a bi-partclampfor rigidly clampt1 0 Fig. 6" isa sectionall vieW of the drivingyunit line 6 6 cf Fig. 3.r

Fig. 7 is a sectional view of the vibratory'unit as mounted on the conehousing taken along the mm1- 1 of Fig. 3. v

as mounted on the conehousing'taken'along the 15 Fig. 8 is a View of thedriving unit, particularly 2 0 piece, armature and'vcoilmem- Uf themagnet, pole bers.

Fig. 9 is a top elevation showing the manner in which the laminations ofthe pole pieces are stamped out of a single strip of` steel-With 2x25minimum of waste inthe strip. z

i Fig. 10 illustrates a'modication of fthe closing plate for thevibratory unit housing.

' In practicing my invention I provide'a loudspeaker having acone-shapedy diaphragm supported, on an annular frame, and asty-lusextend-*fil ing rearwardly Afrom the center ofthe cone.4 vI provide avibratory unit for the -diaphragm to be mounted at thevrear `of the.cone support and comprising a laminated permanent magnet in-` 35 cludinga` plurality of closedring -magnetSfServing as a frame and having acentral aperture kto carry a pair of Y-shaped laminated pole pieceswhich in turn support a laminated armature and :an encircling energizingcoil intermediate saidn40 pole pieces. A driving arm extends from Withinthe armature to the stylus on the diaphragm, `and a non-magnetic housingis providedvaround vthe entiredriving lunit'when assembled on the conesupport.

Referring now` to the drawings, inthe loudspeaker of my invention Iprovide the usual coneshaped diaphragm l0 supported onthe'annular rim ofa frame I.|,` having a pair of rearwardly protruding legs IZJ to carry aslotted mounting strip I3. The strip I3 is preferablyV Welded to thelegs l2 of the frame. A stylusv I4` is Vrigidly secured at the apex ofthe coneto extend rearwardly through the mounting strip. i

Inaddition to obtaining marked :improvement in the lfaithfulness ofreproduction and the volume in the commercial embodiment b'ffmyo marientmagnet comprising a pair of ring-shaped alo the steel issoft enough topermit stamping,

laminations I6 and I1 stamped from a suitable magnet steel preferably inthe shape of a substantially oval ring with an elongated aperture in thecenter thereof. If I wish to increase the field strength I may employfour, or even more laminations in the permanent magnet, using aneven-number so that they may be divided with an equal number on eachside of the pole pieces as will be hereinafterv described. In acommercial embodiment I have stamped the laminations from steelstrips orsheet steel 1/8 inch thick in which but hard enough to provide thenecessary retentivity value. The individual laminations of the magnetare assembled as shown particularly in Figs. 6 and 7 to serve as a frameon the inside and outside ofV a pair of Y-shaped laminated pole piecesI8 and I9 including a plurality of laminations with extendinglegs 2| andan integral tail piece 22. A pair ,of apertures 23 in the tail portion22 of each of the laminations of the pole pieces provide holes thelength of the pole pieces to receive fastening rivets 20.

The individual laminations ofthe pole pieces `I8 and I9 are preferablystamped from relatively thin silicon steel, and with the retainingrivets extending only through the tail portion of the laminations theremight be a tendency for the legs 2| to spread slightly in a longitudinaldirection. To overcome this difficulty I provide silicon steellaminations over the central portion 'indicated by the letter A andsteel laminations of greater thickness at each end as designated by theletter B. This assembly is also indicated by darker and lighter portionsin the pole pieces of Fig. 8. The steel laminations are of suflicientrigidity to prevent the longitudinal spreading of the legs of theintermediate silicon steel laminations when secured together by therivets.

A laminated armature 24 is provided for mounting between the pole piecesand includes a thin knife-edge driving arm 26 having a right-angled,extension 21 of the same area as the laminations for the armature, sothat the arm may be fitted into the center of the armature in thevertical plane of -the stylus I4, to move as an integral portion ofthearmature. Apertures 28 are provided in each of the armature laminationsas well as in the extension 21 to receive retaining rivets to hold thelaminations ofthe armature together. A central aperture 29 is alsoprovided to receive a mounting spring 3| extending the entire lengththereof and protruding a short distance from l each end thereof. Themounting spring is preferably a phosphor bronze alloy, although othermaterials with the necessary flexibility and .strength'may also beemployed. The .mounting spring must of course be stiff enough to insurea faithful movement in response to a variation in impulses applied, andstiff enough so that the armature wont hit against the pole pieces invibI'at-ng'.

As will be noted from a consideration of Figs. 6 and 7, the armaturerocks about the mounting spring 3| as a central axis, although the onlytwisting of the spring that actually occurs is that between the armatureand the torsion blocks as will be hereinafter explained. The mountingspring of course is rigidly soldered into the central vaperture 29 sothere is no relativemovement as between the spring and the armature bodyitself. Torsion or mounting blocks 32 of a non-magnetic metal fit overthe ends of the spring 3| and are slightly spaced away from each end ofthe ar mature body itself to permit vibration of the armature itself,and spaced far enough away so that the block may be soldered to the endof the spring without danger of soldering the block to the endlaminations of the armature. 'Ihe torsion blocks are rigidly securedbetween the ends of thelegs 2| on the pole pieces and are initiallyalined by means of notched portions 33 on each of the four corners ofreach of the blocks 32 to correspond with the ends of the legs 2|. Thetorsion blocks are of such a size that when the armature is mountedbetween the pole pieces, an air gap 34 is provided between the armatureand the ends ofthe pole pieces preferably of .005 inch. From thestandpoint of sensitivity it is of course important to keep this assmall as possible. However,` I have obtained satisfactory operation withan .air gap varying `from .004 to .00'7 inch for instance.

The channel between the `legs 2| of the pole .pieces is of such a sizeas to receive the frame of an energizing coil 3B. The energizing coilhas a central elongated aperture wide enough to permit the insertion ofthe torsion blocks 32 as shown 3 andfi and preferably of particularly inFigs.

such a width thatfthe projections on the blocks willengage the innerinsulating ring 35 on the coil vwhen the pole pieces, armature and coilare clamped together. The energizing coil is wound gwith any desiredwire in the usual manner.

To assure arigid assembly of the pole pieces,

`armature and energizing coil, I employ a bi partspring clamp includinga pair of clamping members 31 and 38 bent to engage the top of the tailportion of the pole pieces at C and D and .rounded out at the corners toremain out of engagement with mounting screws for the entire drivingunit as will be hereinafter described. The

ends of the clamping members are bent outwardly and apertured in theusual manner to receive bolts 39 of non-magnetic material andVpreferably brass. Upon tightening the clamp bolts, the ends of the legsof the pole pieces engage the torsion blocks so tightly that there is,no possibility of looseness or chattering with ,repulsion or attractionof poles of like or opposite polarity, twisting the mounting springtherewith.

A very rapid and simple assembly of the entire unit is provided in firstassembling the laminated pole pieces and laminated armature with the`driving arm therein. The central aperture 29 in i means of the aliningnotches 33.

`ment around the pole pieces.

ei'ipens'i've unit is provided, and at the same time the armature formedbythe various apertures in each of the laminations is of adiameterapproximately the width of the phosphor bronze mounting spring3|. This aperture is reamed out at its ends as shown in Fig. 5 to adepth of approximately 1A; inch. 'Ihe spring 3| is then inserted intothe aperture, a drop of acid asflux is placed in the aperture, and thearmature dipped into a solder bath to rigidly solder the spring into thearmature body. Any excess solder is wiped oiT and the torsion blocks 32are fitted over the "ends ,of the spring, spaced away from thelaminations of the armature. The springs are then soldered to the blockon the outside thereof. After the eld coil 35 is inserted between thelegs of the `pole pieces the armature is placed in the central apertureof the coil 'and properly alined by The clamp is then positioned anddrawn up to a tight engage- A jig is employed for alining the elementsof the assembly.

To prevent dust, dirt or moisture from getting into the driving unit, Iprovide a non-magnetic housing 4l including a closed cap 42 and a bottommember' 43. To complete the assembly of the vibratory unit, the motorassembly comprising the pole piece, armature, and coil, clamped togetherby the bi-part clamp, is positioned between the two laminations I6 andl1 of the permanent magnet with the shoulders 44 on the pole piecesfitting into the alining notches 46 in the laminations. The cap 42 isthen placed over this assembly and the bottom member 43 properlypositioned, after which this assembly is mounted on the mounting strip.I3 by bolts 41. A pair of bolts 48 are insertedthrough the necessaryapertures in the lower portion of the assembly to hold the members ofthe permanent magnet together over the pole piecesand close the housingrover the entire driving-unit. In the meantime the split end 5I of thedriving arm has been placed over the stylus I4 and when soldered theretocompletes the assembly of the driving unit on the cone support. Suitablewireleads 52 extend from the field coil 36 to be soldered to mountingposts 53 eyeletted onto the mounting strip I3. Lead wires 54 then extendfrom the eyelets to the radio receiver.

Inasmuch as dirt and moisture, collecting in the air gap would impairthe operating eiciency, it is very desirable to employ the cap 42 andbottom plate 43 to house the unit. It is understood, however, that thevibratory unit may, if preferred, be mounted directly on the conesupport with the bolts 41 and 48 as described.

.A modication of the bottom member of the housing is illustrated in Fig.10, wherein a fiber insulating strip 56 is assembled in the same manneras the member 43. I also utilize the member 55 as a terminal strip byeyeletting a pair of, terminal lugs 51 thereon. The wire leads 52 arebrought to the eyelets and soldered thereto, and the wire leads 54 fromthe receiver are soldered onto the terminal lugs 51, thus eliminatingthe lugs 53.

'Io further protect the vibratory unit against moisture and dirt whenemploying a housing, I slit a piece of thin surgical rubber 58 andslipit over the driving arm before the unit is placed against the bottommember of the housing. This effectively closes the aperture 59 in thebottom member through which the arm extends.

In providing punched-out laminations for the permanent magnet, andstampings for most of the remaining parts of the vibratory unit, aninlble of long and efficient use.

a very sturdy one. The various parts of the unit are very simple,anddue' to their design may be very readily assembled. It is possible toship the unit disassembled'to its place .of use, and there .35 to bevery quickly and cheaply assembled. The vibratory unit is exceedinglysturdy and capa- Inthe commercial embodiment ofthe invention I obtainmarked improvementv in f reproduction over the entireulo frequencyrange, and a'large increase in volume over the magnetic type speakers inuse at the present time.

Although I have described my invention in its preferredv embodiments, itis understood that 1;-15 aml not limitedthereby, but limit the inventiononly Vby the scopeof the appended claims.

I claim:

1. A vibratory' unit for a magnetic speaker, .in-

cluding a motor assembly having a pair of poleszo pieces, an armaturesupported for oscillatory vibration between the Ypole pieces and havinga driving member in connection therewith, means for yretaining said polepieces rand armature in 'x'ed relation,.and a plurality ofpermanentmag-M25 nets including a continuous, flat, apertured magnet on each oftwo sides of the pole piece'varrnature assembly engaging the polepieces, and of such a size and shape as to extend considerably beyondthe edge of the assembly in oppositefs30 '.directions, and positioned atright angles to the line .of movement of said driving member to serve asa mounting frame for the pole piece 1 armature assembly.

permanent magnet mounted on said motor assembly 'as an assembling frametherefor.

3. A vibratory unit 'for a loudspeaker including a pair of oppositelypositioned Y-shapedy pole pieces each having a pair of forwardlyextending 50 legs with a'channeltherebetween, a tail portion extendingrearwardly from the channel and of the same size assaid channel', anenergizing coil carried in the oppositely positioned channels,anarmature supported between the pole pieces1.55 and 'within the fieldcoil, a` permanent magnet comprising a plurality' of ring-shaped memberswith a mem-ber restingon one side of each pole piece 'taiL'iand anothermember resting on the other sid'eof .each pole piece tail.

4. A vibratory unit for a loudspeaker comprisinga lpermanent magnet, avibrating armature,a laminated pole piece on each of two sides of saidarmature, each of said pole pieces comprising a plurality of `relativelythin Y-shaped laminations having a pair of forwardly extending' legsdening a channel therebetween and a tail piece extending rearwardly fromthe leg pory tion and of substantially the same size as said' channel, aretaining rivet through said tailv pieces, and vmeans for preventing alongitudinal spread of the pole piece lat the leg portions, said meanscomprising relatively heavy laminations assembled'at each end of therelatively light lamina- `tion .assembly with said heavy laminationshav` 75 ing greater rigidity than said relatively light laminations.

5. A loudspeaker motor including an armature, a spindle rigidly securedto said armature, holders carrying said spindle and positioned adjacentto said armature but being slightly wider than said armature, a pair ofpole pieces having their active faces bearing against opposite sides ofsaid holders and accurately spaced by said holders to permit operationof the armature therein, and means for supporting said pole pieces andsupplying magnetic flux thereto.

6. A loudspeaker motor including an armature, separate pole piecespositioned on opposite sides of said armature with end faces toward saidarmature, and .a centrally apertured ring-shaped permanent magnetengaging a side face at right angles to an end face of each of said Dolepieces whereby it may firmly engage both of said pole piecesirrespective of their exact dimensions and rit in the vertical directionthrough the two pole pieces and armature, said pole pieces beinglaminated, and means being provided for clamping all of the laminationsof the pole pieces against said magnet to insure their proper verticalalinement.

7. A vibratory unit for a loudspeaker, including a pair of oppositelypositioned laminated pole pieces, each including a plurality of Y-shaped laminations with a pair of forwardly extending legs having achannel therebetween and a tail portion extending rearwardly from thechannel, an energizing coil, and an armature supported between the polepieces, and a ringshaped permanent magnet in engagement with the polepieces on the tail portion thereof.

8. In a vibratory unit for a loudspeaker, an armature unit comprising apair of spaced apart non-magnetic stationary torsion blocks, asupporting spring rigidly secured at its ends at the blocks, an armaturemember rigidly secured on said spring with the latter extending throughthe longtudinal center of the member from end to end, said membercomprising a plurality of laminations with a one-piece diaphragm drivingelement positioned in said member intermediate the ends thereof andhaving a body portion conforming in shape precisely to the laminationsin said member, with an integral elongated driving arm, flat and of thesame thickness as'the body portion extending away from said body portionin said armature and at right angles thereto for'connection with thediaphragm.

9. A vibratory unit for a loudspeaker including a vibratory armaturecomprising a plurality of apertured laminations, a diaphragm drivingmember having an apertured body portion conforming in shape to saidlaminations and positioned corresponding thereto in said armatureintermediate the ends thereof and a knife-edge elongated driving armextending away from the body portion in the plane of said body portionand integral therewith, and a mounting spring for the armature extendingthrough the aperture in each lamination and the aperture in the bodyportion of the driving member, with said mounting spring rigid withrespect to the laminations and driving member.

10. A vibratory unit for a loudspeaker including a pair of oppositelypositioned Y-shaped polepieces each having a pair of forward legs and atail portion, an apertured energizing coil carried in the recess formedby the legs of the pole-pieces, an armature in the aperture of the coilhaving supporting means carried by the pole pieces,- and an aperturedpermanent magnet carried on a corresponding face of each of the tailportions with a portion of each pole-piece extending into the magnetaperture.

11. A vibratory unit for a loudspeaker including f. 5 a pair of Y-shapedblock-like pole-pieces, each having a pair of forwardly extending legsand a tail portion, with said pole-pieces positioned with the legsfacing each other, an energizing coil carried in the oppositely disposedrecesses in the l0 pole-pieces formed by the legs, and an armaturewithin the energizing coil having a stationary carrying plate at eachend supported by the active faces of the pole-pieces, and a closedsubstantially oval shaped permanent magnet resting on a cor-15,15responding side of each of the tail portions of the pole-pieces, with acorresponding forward leg of each pole-piece lying in the aperture ofthe magnet and acting with the magnet to position the vpole-pieces withrespect to one another and ther-20 armature plate therebetween.

12. A vibratory unit for a loudspeaker including an apertured plate-likepermanent magnet, a vibratory armature, and apair of block-like Y-shaped pole-pieces supporting the armaturel 25 therebetween, eachpole-piece having a recess on at least one side of the tail portioncorresponding in depth substantially to the thickness of the `permanentmagnet with the recesses on corresponding sides of the two tailportions, and said30 permanent magnet lying on the tail portions at thecorresponding recesses with the forward leg on said recess side of eachpole-piece positioned in the magnet aperture.

13. A vibratoryunit for a loudspeaker includingiV35 a pair of spacedapart pole-pieces with the active face of Yeach pole-piece oppositelydisposed from the other, a pair of spaced apart non-magnetic platesbetween the active faces of the pole-piecesn and supported solely byengagement with said* faces, a block-like armature between saidpolepieces and said plates, a spindle irremovably secured to said platesand extending through the armature in the longitudinal axis thereof tosup-,w port the same for vibratory movement, and ai permanent magnetresting upon a corresponding outside face of each pole-piece with suchoutside faces at right angles to the active faces of the pole-pieces,and said magnet acting to position, said pole-piece-armature assemblyelements with"50 respect to one another and acting as a mounting framefor the vibratory unit.

14. A vibratory unit for a loudspeaker comprising a pair of oppositelydisposed single unit.l pole-pieces, a laminated armature mounted be#4tween the pole-pieces for oscillatory Vibration, means for supportingsaid armature comprising a stationary torsion block at each end thereofretained between the pole-pieces in engagementfo With the active facesthereof, a mounting spring irremovably secured at each end in a torsionblock and extending through the armature in the longitudinal axisthereof in a line at right angles to the line of movement of thediaphragm of the 65 loudspeaker.

15. An electromagnetic loudspeaker motor including a continuous ovalshaped permanent magnet having an elongated central aperture, a pair ofopposed pole-pieces positioned against ondface of the magnet with eachpole-piece having a portion extending into the aperture of the magnet toposition said pole-pieces with respect to said magnet, and a clamparound the pole-pieces on an outside face of each at right angles tothe275 magnet engaging face to draw the pole-pieces toward one another.

' 16. An electromagnetic loudspeaker motor having a pair of opposedpole-pieces, an armature unit retained by the pole-pieces between theactive faces thereof, a permanent magnet for the polepieces, and aspring clamp around said pole-pieces enga-ging an outside face of eachparallel to the active face of that pole-piece and adapted to beadjustably tightened to draw the pole-pieces toward one another torigidly retain the armature unit therebetween.

JAMES P. QUAM.

